NEJM: Transmission of SARS-CoV-2 in Domestic Cats

[tetano]

Thanks to Mary Wilson


Transmission of SARS-CoV-2 in Domestic Cats


To the Editor:

Reports of human-to-feline transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)[SUP]1[/SUP] and of limited airborne transmission among cats[SUP]2[/SUP] prompted us to evaluate nasal shedding of SARS-CoV-2 from inoculated cats and the subsequent transmission of the virus by direct contact between virus-inoculated cats and cats with no previous infection with the virus. Three domestic cats were inoculated with SARS-CoV-2 on day 0. One day after inoculation, a cat with no previous SARS-CoV-2 infection was cohoused with each of the inoculated cats to assess whether transmission of the virus by direct contact would occur between the cats in each of the three pairs (Table S1 in the Supplementary Appendix, available with the full text of this letter at NEJM.org). Nasal and rectal swab specimens were obtained daily and immediately assessed for infectious virus on VeroE6/TMPRSS2 cells.[SUP]3[/SUP]
Figure 1.

Virus Titers from Nasal Swab Specimens.On day 1, we detected virus from two of the inoculated cats. By day 3, virus was detectable in all three inoculated cats, with continued detection of virus until day 5 in all cats and until day 6 in two of the three cats (Figure 1).
The cats with no previous infection were cohoused with the inoculated cats on day 1. Two days later (day 3), one of the cats with no previous infection had infectious virus detected in a nasal swab specimen, and 5 days later, virus was detected in all three cats that were cohoused with the inoculated cats (Figure 1). Virus titers in the cats that were cohoused with the inoculated cats peaked at 4.5 log[SUB]10[/SUB] plaque-forming units per milliliter, and virus shedding lasted 4 to 5 days (Figure 1). No virus was detected in any of the rectal swabs tested. Although there have been reports of symptomatic infected cats, none of the cats in our study showed any symptoms, including abnormal body temperature, substantial weight loss (Fig. S1), or conjunctivitis. All the animals had IgG antibody titers between 1:5120 and 1:20,480 on day 24 after the initial inoculation.
With reports of transmission of SARS-CoV-2 from humans to domestic cats[SUP]1[/SUP] and to tigers and lions at the Bronx Zoo,[SUP]4[/SUP] coupled with our data showing the ease of transmission between domestic cats, there is a public health need to recognize and further investigate the potential chain of human–cat–human transmission. This is of particular importance given the potential for SARS-CoV-2 transmission between family members in households with cats while living under “shelter-in-place” orders. In 2016, an H7N2 influenza outbreak in New York City cat shelters[SUP]5[/SUP] highlighted the public health implications of cat-to-human transmission to workers in animal shelters. Moreover, cats may be a silent intermediate host of SARS-CoV-2, because infected cats may not show any appreciable symptoms that might be recognized by their owners. The Centers for Disease Control and Prevention has issued guidelines for pet owners regarding SARS-CoV-2 (www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/animals.html. opens in new tab). Given the need to stop the coronavirus disease 2019 pandemic through various mechanisms, including breaking transmission chains, a better understanding of the role cats may play in the transmission of SARS-CoV-2 to humans is needed.






https://www.nejm.org/doi/full/10.1056/NEJMc2013400?source=nejmtwitter&medium=organic-social

 

[Emily]

A better understanding would be gained from real-life epidemiology, not contrived experimenting on cats in a lab. These experiments sound like the ones done in China.
https://www.sciencemediacentre.org/...ity-of-pets-to-the-covid-19-virus-sars-cov-2/

“It is really critical to remember that these studies were designed to establish animal models for testing of vaccines and drugs, not to establish what happens in everyday life with peoples pets.

“These studies use high doses of virus sprayed into an animals nose or injected into the trachea to induce initial infection, this is not what happens in a house with pets. Colleagues in Hong Kong have been closely monitoring pets there and have so far been a very tiny number of animals[SUP]1[/SUP] (2 dogs and one cat who were not sick) who appear to have contracted a mild infection from their owners. These animals do not appear to have had enough of an infection to actually be able to infect other animals or people. There has been one very similar case reported in one cat in Belgium[SUP]2[/SUP]. This also appears to be what has happened in the well published case of the tigers at New York Zoo (who have contracted a mild infection from one of their keepers). One of the biggest Veterinary clinical pathology companies (IDEXX) have also been conducting qPCR testing on a large number of pets internationally, including in the USA and South Korea and have so far not detected any animals with infection[SUP]3[/SUP].

“There has also been a Chinese study[SUP]4[/SUP] (still in pre-print so not reviewed yet but the methods appear to be robust and the study performed robustly) indicating that a very small number of cats in Wuhan (the centre of the initial COVID-19 outbreak) have antibodies to the virus and indicating they were exposed to it. In this study, 11% of cats tested seem to have been exposed to the virus – note that carnivores sometimes test positive to pathogens from things they have eaten, this doesn’t necessarily mean they were actually infected just that they have had an immune response to it.

“This also happened in the SARs-1 outbreak where a very tiny number of domestic pets tested positive for the virus, probably after contracting it from their owners[SUP]5[/SUP]. Similarly cats and ferrets were able to be experimentally infected with SARs-1[SUP]6[/SUP] with very similar results to the current reports with SARs-2, and so these results are probably not therefore very surprising. There was no indication at all that pets spread SARs-1.

Does this mean cats can catch COVID-19 from humans or vice-versus?

“All the evidence we have so far indicates that domestic cats can in rare cases pick up COVID-19 infections from people but they don’t seem to get seriously ill and don’t appear to pass it back to people. You can never entirely say never, but cats really aren’t playing a role in the spread of the virus. There really isn’t need to be afraid for your cat, or of your cat, or to treat it any differently from any other member of your household during lockdown.